1. Field of the Invention
The present invention relates to a cleaning unit used in an image forming apparatus such as an electrophotographic copying machine and a printer, and in particular, to a cleaning unit which conveys waste toner collected by a cleaning member, a process cartridge using the cleaning unit, and an image forming apparatus using the cleaning unit.
2. Background Art
Conventionally, in an image forming apparatus using, for example, an electrophotographic method, an electrostatic latent image formed on an image carrier such as a photoconductive drum is developed (visualized) with toner by a developing unit, and then the toner images formed by the developing unit are transferred onto a transfer medium such as a paper and an intermediate transfer body by a transfer unit, and toner remaining on the surface of the image carrier is collected by a cleaning unit.
Further, as a cleaning unit, a so-called blade cleaning method, in which a plate shaped cleaning blade is mounted, to a periphery of an opening of a cleaning housing which is open toward the image carrier, and the cleaning blade scrapes off residual toner on the image carrier by bringing the cleaning blade into contact with the image carrier to thereby collect the toner in the cleaning housing, has been widely adopted.
However, except for a case in which waste toner scraped and collected by the cleaning blade immediately falls downward, this kind of blade cleaning methods has drawbacks. That is, in a structure in which the cleaning blade is disposed to face a rotational direction of the image carrier and the rotational direction of the image carrier is downward from above, waste toner scraped and collected by the cleaning blade inevitably is place on an upper portion of the cleaning blade.
A technique for preventing a case, in which waste toner scraped and collected by the cleaning blade is placed on the upper portion of the cleaning blade to damage a waste toner collecting operation due to a cleaning member, and for conveying the waste toner scraped and collected by the cleaning blade to a waste toner accommodating part located at an inner side of the cleaning housing by using a waste toner conveying member, has already been proposed.
As such a technique, for example, a technique in which a rotary driving part is provided above the upper portion (serving as the waste toner storage part) of the cleaning blade and the waste toner conveying member is rotated by the driving part such that the waste toner accumulated in the waste toner storage part is conveyed toward the waste toner accommodating part has been proposed (see JP-A-10-301460).
Further, as another technique in the related art, for example, as shown in FIG. 19A, a technique in which a waste toner conveying member 515 extending between a waste toner accommodating part 512 inside a cleaning housing 511 and the upper portion (waste toner storage part) of the cleaning blade 513 is provided, a rotary driving part 520 (for example, using a crank arm) is provided at a waste toner accommodating part 512 side of the waste toner conveying member 515, the waste toner conveying member 515 is slidably supported by a supporting member 521, and a free end of the waste toner conveying member 515 is rotated to convey the waste toner accumulated in the waste toner storage part toward the waste toner accommodating part 512 has been proposed (see JP-A-2002-123143 and JP-A-2003-162191).
Furthermore, as the waste toner conveying member 515, for example, as shown in FIG. 19B, one in which a frame member 516 has a multi-stage frame structure and openings 517 are provided in the frame member 516 so as to perform waste toner conveying operations at a plurality of places. In FIG. 19A, reference numerals 500, 501, and 502 denote an image carrier, a charged roll, and a cleaning unit, respectively.
However, in each of the cleaning units disclosed in JP-A-10-301460, JP-A-2002-123143 and JP-A-2003-162191, a portion for serving to convey waste toner is rotated by the waste toner conveying member, so that the portion for serving to convey waste toner comes in only line-contact with the waste toner storage part (upper portion of the cleaning blade). Even though a plurality of portions for serving to convey waste toner is provided, the conveying efficiency of the waste toner on the waste toner storage part is apt to be insufficient.
In addition, a large upper space of the waste toner storage part needs to be secured in order to allow the rotary movement of the portion for serving to convey waste toner, which increases the vertical length of the cleaning housing. As a result, a technical problem in which the cleaning unit becomes large occurs.